Radio receiving system



y G. P. ADAIR 'vRe.'21,1`5l- RADIO RECEIVING sYsTEl original Filed sept.s, 1951 4 sheets-sheet 1 NYENTOR. @gorge dday;

BY g. UTK AToRNEY l July 18, 1939.

July 18, 1939. v G. P. ADAIR R 21,151

RADIO RECEIVING SYSII'EI original Filed sept. e, l1951 4 sheets-sheet a39 36 a7 i' 50 Z5 4/ 0^@ u j 47 4/7 4/4 v e n) N BY A'TTQRNEY July 18,1939. cs. P. ADAIR RADIO RECEIVING SYSTEI 4 sheets-sheet, s

Original Filed Sept. 8, 1931 INVENTOR. yggfyedaag N PI 11.11

ATTORNEY m IIH July 18, 1939. cs.` P. .4m/MF:

I RADIO RECEIVING SYSTEl Original Filed Sept. 8, 1 951 4 Sheets-Sheet 4IN V EN TOR.

W, d A ,Pf 6

A TTORNEY seated Jul-y 1s, 1939 RADIO RECEIVING SYSTEM George P. Adair,Takoma Park, Md.

Original No. 1,949,136, dated February 27, 1934,

Serial No. 561,758, September 8, 1931. Application for reissue February26, 1936. Serial No.

33 Claims.

My invention relates broadly to radio receiving systems and moreparticularly to a novel circuit arrangement for radio broadcastreceivers.

One of the objects of my invention is to provide 5 a circuit arrangementfor a radio broadcast receiver having means for controlling theoperation of the circuits of the receiving system according to thecharacter of the received signals.

` Another object of my invention is to provide a signal receiving systemhaving means for controlling the response of the reproducing circuit bymeans of variations in modulated amplitude of the received signalingenergy.A

A still further object of my invention is to provide a circuitarrangement for a signal receiving system in which the operation ci' thereproducing circuit depends upon the' characteristics of the modulatingsignal or other energy incident upon the reproducing circuit.

Another object of my invention is to provide a circuit arrangement for aradio broadcast receiver having means for controlling the response ofthe receiver to musical programs and short announcements whileeliminating programs constituted by extended speeches or advertisingtalks.

Still another object of my invention is to provide a circuit arrangementfor a radio receiving system having means for discriminating betweenprograms of extended speech and advertising, and programs of musicalselections or vocal renditions in order to meet the preference of manylisteners who do not desire to listen to programs of continuous speech.

A further object of my invention is to provide a control circuit foroperation with a radio broadcast receiver for discriminating againstprograms of musical variety and programs constituted by extended speechand advertising talks with means for automatically tuning the receivingapparatus to programs of music while rejecting programs of speech andadvertising talks.

A still further object of my invention is to provide a circuitarrangement for a radio broad'- cast receiver automatically operativeupon receipt of speech programs for disconnecting the radio broadcastreceiver and connecting an automatic phonograph or other automatic soundreproducing system to the audio frequency amplification circuits ofthereceiver to insure a continuous musical program Without interruption byextended advertising talk and speech.

Another object of my invention is to provide an automatic controlcircuit operative to discriminate between voice programs and musicalprograms received over a radio receiving circuit with switching meansfor automatically tuning the receiving apparatus either to a signalingchannel on which music is being received or to a control circuitextending from an automatic phonograph or other form of automaticprogram storing apparatus, such as the telegraphone. silent motionpicture, or motion picture with sound.

Other and further objects of my invention reside in the radio receivingsystem and associated control circuits set forth in the speciiicationhereinafter following by reference to the accompanying drawings, inwhich:

Fig. 1 diagrammatically illustrates a circuit arrangement for a radiobroadcast receiver embodying the principles of my invention; Fig. 2shows a circuit arrangement for. a receiving apparatus embodying myinvention in which automatic switching means are provided for switchingthe audio frequency amplification :system of the receiving apparatus toa control circuit leading from an automatic phonograph or otherautomatic program storing device while the radio receiving apparatus isdisconnected during the transmission of speech programs; Fig. 3illustrates a modiied circuit arrangement embodying my invention inwhich means for automatically selecting another station transmitting amusical program is provided when an extended voice program isencountered on one signaling channel; and Fig. 4 shows a number oftypical sound wave traces which explain the operation of the radioreceiving apparatus of my invention.

In the receiving system of my invention I employ a system of tunedcircuit for the reception of signaling energy in connection with anampliiication and sound reproduction system. Supplementin'g thedetection and amplier circuits I provide an auxiliary control circuitwhich discriminates in its operation between signaling energy resultingfrom musical programs and signaiing energy resulting from voiceprograms. In the auxiliary control circuit of my invention I provide arelay arrangement by which the bias potential upon a control grid of acontrol tube may be governed in accordance with the character of theincoming signaling energy. The output circuit of the control tubeoperates a relay v system which may perform many functions such as theopening of the sound reproducer circuit,

' former 4.

tuning the receiving apparatus to some other signaling channel on whichmusical programs may be received. Y

The `characteristics of the speaking voice are such that there arenumerous and definite pauses between syllables and words as well as thelonger pauses between phrases and sentences while in vocal andinstrumental music (except in very exceptional cases) there are fewdefinite pauses. If the electric waves corresponding to the abovementioned signals are rectied it is found that in the case of speech apulsating `current is obtained while in the case of music .it is adirect current of moderately varying amplitude.

The character of the audio frequency signals to which the controlsystem-responds is further differentiated by an arrangement of selectivelter so that the average frequency of speechwhich is lower than theaverage frequency of music produces different conditions in theoperation of the relay system which correspondingly controls theswitching mechanism.

Referring to the drawings in detail, the system includes a receivingcircuit having an antenna ground connection shown at I-2 in Fig. 1.'I'he antenna ground connects to an input circuit including primaryWinding 3 of the coupling trans- Secondary winding 5 of couplingtransformer 4 is tuned by variable condenser 6. The tuned circuitconnects to the input system of a radio frequency amplifier includingelectron tubes 1, 3 and 9. The detector tube III connects to the outputcircuit of the radio frequency amplifier system. The tuning elements 6,II, I2 and I3 for the radio frequency stages and the detector stage ofthe receiving system are simultaneously controlled as indicated throughdotted line I4. The output circuit of the detector tube I0 connects tothe audiofrequency amplifier system constituted by electron tubes I5 andI6 connected in parallel for obtaining greater power output. The outputcircuit of the audiofrequency amplifier stages I5-I6 include theaudiofrequency transformer I1, the primary winding of which is indicatedat I8 connected to the output circuit of tubes I5 and I6 through thecoupling condenser 51 and the secondary winding of which is indicated atI9 connected to the sound reproducer designated at 20. The movable coil2I of the electro-dynamic speaker system constituting the loud speaker2l! is connected in series with contactr22 of a relay system indicatedat 23 and which will be described hereinafter. The eld winding of theelectro-magnetic sound reproducer 2D is shown at 24 suitably energizedfrom the power supply system formed by the rectier circuit 25.

A path or connection is taken from the output circuit of the detectortube Ill as shown at 26. This connection is not necessarily made atlthis point but may be made prior to the detector stage, as shown byFigs. 2 and 3, or may be made afterV the detector stage as conditionswarrant. This path or connection leads to an auxiliary control tube 21,the input circuit of which is provided -with a selective filter couplingdevice including capacity elements 2B and 30 and inductive element 23. Acoupling resistor 3| is provided for completing the input circuit to theauxiliary tube 21. filter more effective an inductive element similar to29 may be substituted for resistor 3I. Additional lter stages may beadded if conditions make it desirable. 'I'he grid 21c of control tube 21is normally biased to a negative potential ot such value that the .tubeis operating on or below If it is desired to make the selective thelower knee of the characteristic grid voltageplate current curve. Thisnegative potential is provided through resistor 3| connected to theground which is maintained at a negative potential with respect tocathode 21a by means of the voltage drop due to a current flow throughresistor- 43, the circuit of which is completed through resistor 50 andconductor 34 to the power supply which will be hereinafter described.Capacitor 5I serves as a by-pass or smoothing condenser.

The output o1' the control tube 21 leads from the anode 21h to thesolenoid winding 32 forming part of a relay. Solenoid 32 has its circuitcompleted with a resistance element 33 which leads through conductor 34to the power supply circuit. Suitable by-pass or smoothing condensers 35and 36 are connected to given points o1 the output circuit and ground asshown.

The relay 32 controls the movement of armature tongue 31 which shiftswith respect to contacts 33 and 39. A vacuum tube relay has beenindicated at 4I having an input circuit extending through the conductorindicated at 42 which connects to tongue 31 of the relay. Movement ofthe armature or tongue 31 against contact 33 places an increasingnegative potential on the grid 4Ic of tube 4I by allowing a negativecharge to collect on the grid condenser indicated at 41 through theresistance and connection to ground which is normally maintained atnegative potential with respect to the cathode 4Ia through resistance 4las previously explained relative to tube 21. The placing of the negativecharge on` grid 4 Ic of tube 4I results in reducing the plate current inthe output circuit leading from the anode 4Ib' through relay windlng-23in the output circuit which is completed through resistance 33 to thepath of*v condition for the reception of a program such as i vocal orinstrumental music.

When armature tongue 31 is in contact with contact 38, a given perioddepending on the values of resistance 45 and capacitance 41 and thecharacteristics and operating constants of the tube employed, the chargewill be reduced by leakage through resistance 45 until the potential ongrid 4Ic is of such an order as to allow suflcient current to flow inthe output circuit to energize relay 23 and thereby open the circuit tothe voice coil v of the loud speaker rendering it inoperative. 4

The control circuit of my invention makes use of the fact that thespeaking voice is distinguished from vocal or instrumental music by the`differences in rate and duration of the impulses and pauses intheincoming wave trains. These ydiierences are brought out by operation oi'the rectiner circuit as hereinbefore explained.

The characteristics of the audio frequency signals to which the controltube 21 and the relay 32 will respond are further differentiated byreason of the cut-off afforded by the ilter elements 23, 29 and 30. Inother words. the average irequency of speech is lower than the averageIre'- quency of music. An arbitrary cut-ot! value o! 512 cycles has beenchosen as a suitable frequency since this is the second harmonic of theaverage fundamental frequency of a womans speaking voice. This iiltercan easily be made adiustable for local conditions. The results of thisdiscrimination between music and speed is to cause the output current oftube 21 to be practically constant on the reception of music therebycausing relay l2 to be energized the major portion of the time drawingarmature 31 down and establishing connection with contact 39 therebyplacing a negative charge on the grid 4Io and cutting off the platecurrent in the output circuit of tube 4|, de-energizing relay I3 andenabling the voice coil circuit to be closed for the reception of music.However, upon the reception of extended speech, the solenoid winding l2is de-energized toa greater extent allowing armature 31 to contact with3l more than with 39 thereby allowing the charge on capacitance 41 andthe grid 4Ic to be discharged through resistance 45 and conductor 4l tocathode 4Ia of tube 4I. This allows plate current to flow in the outputcircuit of Vtube 4I energizing relay 23 and thereby disconnecting thevoice coil of the loud speaker. In this way, the receiver automaticallyresponds to the broadcast program so long as instrumental music or vocal'selections are being transmitted. The receiver automatically does notrespond when speech is prolonged on the broadcast program. The powersupply for all of the electron tubes is obtained from the circuitthrough a transformer system 52 having a plurality of windings 53, 54,55.and 56 leading to the different power supply circuits of the receiverand to the rectifier 25 from which the platepotential, biasing potentialand potential for exciting the field winding 24 of the electrodynamicspeaker is obtained. In the event that it is not desired to interruptthe entertaining properties of the receiving apparatus, I may employ thearrangement shown in` Fig. 2 where the sound reproducing system isswitched to an automatic phonograph or other form of automatic programrecording device which will permit the reproduction of a desired recordintermediate the periods of entertainment broadcasting on the radioreceiving system. Reference to Fig. 2 shows the system I employ forswitching the audio-frequency amplifier portion of the broadcastreceiver to the control portion of a recorder circuit by which recordedprograms are reproduced electrically. In this arrangement, an auxiliaryunit is coupled to the output circuit of the radio frequency amplifierstage 9 and connected to a relay control system which functions toconnect the phonograph actuating circuit into the input of the detectortube for utilizing the detector tube as part of the audiofrequencyamplifier system for reproduction of music from the phonograph circuitwhen broadcast music is not being received. 'This arrangement includesthe radio frequency detector stage indicated at which is coupled throughconductor 5| and coupling condenser 62 with the output of the radiofrequency amplifier stage Q. The other side of the input circuit to theradio frequency detector stage i6 is completed through the impedancecircuit 63 to ground as shown. 'Ihe output of the radio frequencydetector stage 60 is coupled through the coupling circuit 64 with theinput circuit of the audiofrequency rectifier tube 65. A filter circuitis employed between the output` circuit'of the yradio frequency detector60 and the input circuit of the auxiliary detector tube 65 in amannersimilar to the flltercircuit hereto'- withdrawn from contact withcontact 68 and connects with contact 89. This places the phonographpick-up 1| or telegraphone 1in in circuit with the input of detectortube I0 and at the same time short circuits the input to detector tubeIl) from the radio frequency amplifier by shunting the coupling circuitIl through leads i3d. Simultaneously contact '68 makes contact withcontact 'III placingresistance 'l2 in parallel with resistance Il andthereby reducing the negative biasing potential on detector tube Il sothat it operates on the straight portion of the characteristic curveinstead of the lower knee of the curve, hence employing it as a linearamplifier.

Terminals indicated at -|4 connect to contacts on the record releaseswitch on the phonograph or reproducing device where a soundprogram suchas the telegraphone is employed, this fea-'- ture is obtained byemploying an interlocking time switch, or a mechanical or electricaldevice or impulse on the recording wire to render ythe radio receiverresponsive at the completion of one or more recorded selections, so thatwhen the musical program is continued on the radio receiver it will notinterrupt the playing of the record. This, of course, is optional andmay be eliminated in which c ase as soon as the radio musical program isresumed, the phonograph will be disconnected and the radio circuitsrestored to normal. i

Switch 'I5 is closed when it is desired to render the speech-eliminatingsystem inoperative or'in other Words, when the apparatus is to performas a normal radio broadcast receiver.

In Fig. 3, I have shown equipment which will automatically selectanother station when the musical program is discontinued on the stationtuned in at the moment. If, after a given period,

no music is received, another station will be selected. If the programof this station `is interrupted too long, still another station will beselected or a recorded program may be used similarly to that shown inFig. 2 and hereinafter described. The Wiring of the equipment is similarto that shown in Fig. 2 and similar reference characters have beenemployed.

When extended speech is received or in the event of an interrupted ordiscontinued program, relay 23 will be energized as previouslydescribed. Contacts 11 will be closed completing a circuit through relay18 which actuates selector switch 79. Switch 'i5 is closed to cut outthe relay control system when desired. Circuit 16 connects to a releaseswitch on thephonograph ll or telegraplione 'Ha to permit a full recordto be played before returning the sound reproducing system to the radioconnection. If station selector equipment operates practicallyinstantaneously contacts 8l may be used to place a bias on the grid Maof tube M to prevent another operation of relay 'i8 before the selectorhas operated and to place the relay system in position to operate againif there is no music on the station for which the radio frequencyamplifier circuits have just l lli been tuned to resonance. If theselector equipment l0 is of a type that requires an appreciable time tooperate it is advisable to also connect terminals l2 to contacts whichare closed only while the selector device 80 is operating. If, after agiven time, depending on the constants vof resistance and capacitance I1and the characteristics operating constants ofl the tube employed, nomusic is received the relay 23 will be operated again and anotherstation selected. When the selector switch 1l reaches contacts I3, inthe course of its clock-wise movement, relay Il is energized operatingcontacts i1, il, 69 and 1li as previously described to disconnect theradio receiving circuit by shunting coupling circuit I3 and connectingthephonograph pick-up 1| or telegraphone 1Ia to tube Il. Contacts 66close starting the circuit of the automatic phonograph 1I ortelegraphone lla. Contacts I5 are closed which completes a circuitthrough terminals I6 to momentary contacts on the phonograph recordrelease switchor other indicating vdevice so that the selector switch 19will be actuated when the record is completed. When' the selector switchcontacts makes contact with contacts B1, relay IB is energized allowingvthe selector to return to the first position 89 and the circuits to tubelli are restored to normal.

Switch 90 is opened if it is desired to remain tuned on the same stationbut to eliminate extended speech. If it is desired to substitutephonograph records for the extended speech, switch 90 is closed tocontact 9| and switch 92 is closed. If it is desired to render thedevice entirely inoperative, switch 15 is closed. Contacts 92 open thecircuit to the loud speaker when it is desired only to eliminateextended speech and not substitute any other program. Relays 18 and 88are of the quick acting slow release type in order to insure fulloperation of the selector switch.

A multipoint switch operated by a single control may be used for theswitching operations described above.

The radio frequency detector tube circuit 60 may be used as a volumecontrol system for changing the voltage on the screen grid of the tubesof the radio frequency stages or the circuit may be used to actuate theautomatic coupling device as set forth in my application Serial No.548,695, filed July 3, 1931, entitled Volume control system.

The system of my invention utilizes another difference in thecharacteristics of music and speech for discriminating between them,namely that the periods of no signal'in speech integrated over apredetermined period of time, are more pronounced than similar periodsduring music reception. 'I'his is illustrated in Fig. 4. At A is shown atypical Wave trace of speech. It will be noted that there are extendedperiods during which the amplitude is zero or very small. By utilizingthe characteristic v differences of the major frequencies found inspeech and music, that is, where the low frequencies predominate to arelatively greater extent in speech than in music, the silent period canbe increased to a still greater extent in speech than in music. The

wave trace A shows considerable pause between` The pause between wordsis usually charge and discharge resistors 40 and I5, respectively,contacts 38, will remain closed for a greater part of the time thancontacts 3! (this may be only relatively speaking depending on the ratioof the time constants of the charge and discharge circuits) therebyallowing the negative charge on the condenser 5I and hence the negativebias on grid llc to be reduced to such an extent as to allow a currentof sucient value to operate relay 23 to iiow which would render the loudspeaking or other reproducing device inoperative by opening the circuitto the voice coil 2l at contacts 22.

Wave trace C" shows the same traces for an average musical selection. Inthis case, although the peaks in the speech may, incertain instances behigher than those ,in music, the average amplitude ofthe musicintegrated over a predetermined period of time is higher and moreconstant with very few extended periods of no signal. For this reason,during musical selections or when musical selections are commenced aftera period of silence or extended speech, relay 32 will be operated agreater portion of the time than during speech (this may be onlyrelatively speaking depending on the time constants of the charge anddischarge circuits) which will allow a negative charge to accumulate onthe condenser 5I and grid llc, thus controlling the plate circuit oftube 4I to such an extent as to render relay 23 inoperative and the loudspeaker or other reproducing de'vice operative by closing the contacts22 and completing the circuit through voice coil 2l.

The system of my invention has wide application in the art for purposesof governing the operation of a reproducing circuitwith respect to asignal receiving circuit under control of diierences in the modulatingsignal energy or other energy incident upon the reproducing system. Forexample, the system of my invention provides means for controlling theoperation of the reproducing system by such energy as is developed bynoise arising in the several associated electron tube circuits, asdistinguished from the desired signal energy. The reproducing system maybe rendered unresponsive under conditions of excessive noise while beingrendered operative under conditions'of normal signal energy.

While I have described my-invention in certain preferred embodiments, Idesire that it beA understood that modifications may be made and that nolimitations are intended other than are imposed by the scope of theappended claims.

What I claim and desire to secure by Letters Patent of the United Statesis as follows:

1. In a radio receiving system, means for receiving signaling energy, asound reproducing system, an auxiliary control circuit connected withsaid signal receiving means and means controlled by said auxiliarycontrol circuit for discriminating against programs of substantiallyintermittent character and substantially continuous character receivedby said signal receiving means for correspondingly controlling thecontinuity of the circuit between said signal receiving means and saidsound reproducing system. P

2. In a signal receiving system, means for receiving signaling energy, asound reproducing circuit an auxiliary controll circuit connected withsaid signal receiving means, a relay device operated by said auxiliarycontrol circuit, said relay device operating -according to thesubstantially continuous and subsantially intermittent character of theprogram received by said signal susi receiving means for controlling thecontinuity of tem and said signal receiving means.

3. In a signal receiving system, a circuit for receiving signalingenergy constituting programs of substantially intermittent andsubstantially continuous characteristics. a sound reproducingl systemconnected with said circuit, an auxiliary control circuit connected withsaid receiving circuit, a relay operated by said auxiliary controlcircuit, said relay operating to open or close the circuit through saidsound reproducing system with respect to said receiving circuitsaccording to the substantially intermittent or substantially continuouscharacteristics of the programs constituting the received signalingenergy.

4. In a signal receiving system, a circuit for receiving signalingenergy constituting programs of substantially intermittent andsubstantially continuous characteristics, a sound reproducing circuit,an auxiliary control circuit connected with rst mentionedcircuit, arelay operated by said auxiliary control circuit and means controlled bysaid relay for electrically connecting or disconnecting said soundreproducing circuit with respect to said signal receiving circuitaccording to the substantially continuous or substantially intermittentcharacteristics of the programs constituting the received signalingenergy.

5. In a radio broadcast receiving system, a signal receiving circuitresponsive to speech or musicalprograms, a sound reproducing system, anauxiliary control circuit connected with said rst mentioned circuit, arelay operated by said auxillary control circuit, means connected withsaid auxiliary control` circuit for discriminating between averagefrequencies of speech programs and average frequencies of musicalprograms. relay operating to control the electrical tion of said soundreproducing circuit with said signal receiving circuit in accordancewith the character of the received program.

6. In a radio receiving system, means for receiving signaling energy, asound reproducing system, an auxiliary control circuit connected withsaid signal receiving means and means controlled by said auxiliarycontrol circuit for discriminating between speech programs and musicalprograms received by said signal receiving means for controlling theelectrical circuit between said signal receiving means and said soundreproducing system and rendering said sound reproducing systeminoperative with respect to said signaling energy vduring the receptionof the speechprograms and operative during the reception of musicalprograms.

7. In a signal receiving system, means for receiving signaling energy, asound reproducing circuit, an auxiliary control circuit connected withsaid signal receiving means, a relay device operated by said auxiliarycontrol circuit, and an electron tube circuit controlled by said relaydevice, said electron tube circuit being variably biased according tothe character of the program v'received by said signal receiving meansfor controlling the continuity of the circuit between said soundreproducing system and said signal receiving means for correspondinglycontrolling the operation of said sound reproducing system.

8. In a signal receiving system, acircult for receiving signaling energyconstituting programs of substantially intermittent and substantiallycuit, a relay operated by said auxiliary control circuit, an electrontubecircuit connected with said relay' and controllable according to thebias potential impressed thereon and switching means controlled by saidrelay and operating to open or close the electrical circuit through saidsound reproducing system according to the substantially intermittent andsubstantially continuous characteristics of the programs constitutingthe received signaling energy for correspondingly` tem an'd a circuitcontroller in said output system operating to electricallyl connect ordisconnect said sound reproducing circuit with respect to said signalreceiving circuit according to the 'character of the received signalingenergy for correspondingly controlling the operation of said soundreproducing circuit.

10. In a radio broadcast receiving system, a signal receiving circuitresponsive to speech or musical programs, a sound reproducing system, anauxiliary control circuit connected with said first mentioned circuit,an electron tube operated by said auxiliary control circuit, 'a relayoperated by aid electron tube, means connected "with lary controlcircuit for controlling the bias iai impressed upon said electron tubefor selectively controlling said relay for discriminating betweenaverage frequencies o speech programs and average frequencies of musicalprograms, said relay operating to control the electrical connection ofsaid sound reproducing circuit with respect to said signal receivingcircuit in accordance with the character of the received program.

l1. In a signal receiving system, a signal receiving circuit, a controlcircuit connected With said signal receiving circuit, a relayelectrically operated by said control circuit, means controlled by saidrelay for selectively tuning said signal receiving circuit, and means insaid control circuit for maintaining said relay in one condition.,

upon receipt of musical productions and in another condition uponreceipt of voice programs of predetermined length.

l2. In a signal receiving system, a signal receiving circuit, a soundreproducing circuit connected therewith, a control circuit operated fromsaid signal receiving circuit, a relay electrically actuated by saidcontrol circuit, a ltercircuit interposed between said control circuitand said relay for discriminating between average voice frequencies andaverage musical frequencies, said relay being operated under differentconditions upon receipt of extended speech programs as distinguishedfrom musical programs for correspondingly controlling the operation ofsaid sound reproducing circuit with respect to said signal receivingcircuit.

13. In a signal receiving system having means for'discriminating betweenvoice programs and musical programs, a signal receiving circuit, a soundreproducing circuit connected with said signal receiving circuit, anelectron tube control circuit. a relay electrically operated by saidcontrol circuit, means for biasing said electron tube control circuit toa predetermined cut-olf value for deriving a direct current variationcorresponding to theincoming signalling energy, means dispom in saidelectron tube control circuit responsive to a greater extent tomusicalfrequencies than voice frequencies whereby the average current suppliedto said relay is greater upon the reception of musical frequencies thanupon the reception of voice frequencies, the character of the musicalfrequencies being substantially continuous as distinguished from theintermittent pauses inherent in the voice frequencies, whereby the relayis energized a greater proportion of the time during the reception ofmusic frequencies than during the reception of voice frequencies forcorrespondingly controlling the connection of said sound reproducingcircuit with said signal receiving circuit.

14. In a signal receiving system, a signal receiving circuit, a soundreproducing circuit connected with said'signal receiving circuit. a conyed with said relay, Vand means for impressing f ceiving signalingenergy, an electron tube device predetermined biasing potential uponsaid electron tube, said means operating to change the biasing potentialupon said electron tube according to the character of the incomingprogram whether a voice program or a musical program for controlling theoperation of said relay and correspondingly controlling the connectionof said sound reproducing circuit with said signal receiving circuit.

15. In a signal receiving system, a signal receiving circuit, a soundreproducing circuit, a relay system for controlling the connection ofsaid sound reproducing circuit with saidsignal receiving circuit, acontrol circuit electrically connected with said signal receivingcircuit, an electron tube including a cathode, a control grid and ananode, said control grid being connected with said signal receivingcircuit, said anode being connected with said relay system, and meansfor changing the bias potential on said control grid according to thecharacter of the incoming program for actuating said relay system in onecondition upon the reception of musical programs and in a differentcondition upon the reception of voice programs for correspondinglycontrolling the connection of said signal receiving circuit with saidsound reproducing system.

16. In a signal receiving system, a,.signal receiving Icircuit, a soundreproducing circuit, switching means for controlling the connection ofsaid sound reproducing circuit with said signal receiving circuit,automatic means for selectively tuning said signal receiving circuit todifferent signaling channels, a control circuit connected with saidsignal receiving circuit, a relay electrically actuated by said controlcircuit for controlling said switching means and said automatic meansaccording to the character of the incoming program for maintaining saidsound reproducing circuit in connection with said signal receivingcircuit on a signaling channel carrying a musical program asdistinguished from a voice program. Y

17. In a signal receiving system. a signal rcceiving circuit responsiveto a mmapueity of anferent signaling channels over a predetermined rangeof frequencies, a sound reproducing circuit electrically connected withsaid signal receiving cuit operative according to the character of theincoming program for actuating said relay system for selectively tuningsaid signal receiving circuit to a signaling channel carrying a musicalprogramas-distinguished from signaling channels carrying a speechprogram for correspondingly actuating said sound reproducing circuit.

18. In a signal receiving system, means for receiving signaling energy,an electron tube device connected with said means, a reproducing system.and time delay means connectible with said electron tube device forcontrolling the transfer of energy between said reproducing system andsaid first mentioned means.

19. In a signal receiving system, means for re- Y ceiving signalingenergy, an electron tube device connected with said means, a reproducingsystem, an electrical network connectible with said electron tubedevice, and means controlled by said electrical network for controllingthe transfer of energy between said reproducing system and said firstmentioned means.

20. In a signal receiving system. means for reconnected with said means,a reproducing system, an electrical network connectible with saidelectron tube device, and a potential operated. device connected withsaid networkl and operative for controlling the transfer of energybetween said reproducing system and said nrst mentioned means.

21. In a signal receiving system, means for receiving signaling energy,an electron tube` device connected with said means, a reproducingsystem, and a multiplicity of time delay devices controlled by ,saidelectron tube device for controlling the transfer of energy between saidreproducing system and said rst mentioned means.

22. In a signal receiving circuit, an energy transfer channel, areproducing system, and means for connecting or disconnecting and forcontrolling the energy transfer between said reproducing system withrespect to said energy transfer channel comprising a frequencydiscriminating circuit, a'time delay network connected with saidelectron tube, and a device controlled by said time delay network andinterposed in circuit between said energy transfer channel and saidreproducing system.

23. In a signal receiving system, "an energy transfer channel, areproducing system, and means for controlling the transfer of energybetween said energy transfer channel and said reproducing systemcomprising a multiplicity of coupled electron tube circuits and timedelay circuits interconnected therewith.

24. In a signal receiving system, means for receiving signal energy, areproducing circuit, and means for controlling the transfer of energybetween said reproducing vcircuit and said means comprising a. frequencydiscriminating circuit, an electron tube connected therewith, a time'delay network connected with said electron tube, elecelectron tube meanscontrolling elements common c x v 21,151

` to said sound reproducing circuit and said first mentioned means.

25. In an apparatus for reproducing selected signals from substantiallyintermittent and substantially continuous composite signals, an energytransfer circuit, a reproducing circuit, means for controlling theeffective circuit between said energy transfer circuit and saidreproducing circuit comprising an electron discharge tube, and means forcontrolling the bias potential on said electron tube 'according to thesubstantially intermittent or substantially continuous character of theenergy incident on said transfer circuit for determining the transfer ofenergy from said energy transfer circuit to said reproducing circuitwithout interrupting the continuity of said circuit.

26. In an apparatus for reproducing selected signals from substantiallyintermittent and substantially continuous composite signals, an energytransfer circuit, a reproducing circuit, an electron tube having inputand output circuits, a connection between said output circuit and saidreproducing circuit, a connection between said input circuit and saidenergy transfer circuit, and means controlled by the substantiallyintermittent or substantially continuous character of the energy in saidenergy transfer circuit for determining the bias potential on saidelectron tube for correspondingly controlling the operation of saidreproducing circuit. j

27. In an apparatus for reproducing selected signals from substantiallyintermittent and substantially continuous composite signals, an energytransfer circuit, a reproducing circuit, an electron tube having inputand output circuits, a. connection between said output circuit and saidreproducing circuit, a connection between said input circuit and saidenergy transfer circuit, and time controlled means Operative accordingto the substantially intermittent or substantially continuous characterof the energy incident upon said energy transfer circuit for determiningthe bias potential and time period of impression thereof upon saidelectron tube for correspondingly controlling the operation of saidreproducing circuit.

28. In `a signal substantially intermittent and substantially oontinuouscharacter, an energy transfer channel, a. reproducing circuit, meansinterconnecting said channel with said circuit, and a multiplicityofbias controlled electron tube circuits forint/.errupting the effectivecircuit between said channel and said circuit according to the substan-ftially intermittent or substantially continuoucharacter of the signalenergy incident upon said channel.

29. In a signal receiving system for signals of substantiallyintermittent and substantially continuous character, an energy transferchannel, a reproducing circuit, means interconnecting said channel-andsaid circuit, and means coacting with the aforesaid means fordiscriminating against undesired signal energy of substantiallyintermittent character while maintaining the effective continuity of thecircuit between said channel and said circuit for the continuousreproduction of signal energy having predetermined desired continuouscharacteristics.

.30. In a signal receiving system, means for receiving signaling energy,a reproducing system, an auxiliary control circuit connected with saidsignal receiving means and means controlled by said auxiliary controlcircuit and operative according to the frequency of the modulation of32. In a signal receiving system, means for re-w ceiving signalingenergy, a. reproducing system. an auxiliary control circuit connectedwith said signal receiving means and means controlled by said auxiliarycontrol circuit and operative according to the continuity of themodulation of the signal or other energy incident upon said rstmentioned means for correspondingly .controlling the transfer of energyfrom said first mentioned means to said reproducing system.

33. A transmission channel for transmitting composite energy includingregularly transmitted ,l l signaling impulses and regularly transmittedand receiving'systen'i for signals of modulated control impulses, meansfor integrating the effects of said modulated control impulses over apredetermined time period independently of said signaling impulses,means for reproducing said signaling impulses, and control meansactuated by the integrated effects of said modulated control'impulsesfor controlling the operation of saidlast mentioned means.

1 GEORGE P. ADAIR.

